The present invention relates to a cushioned mounting device, and more particularly, to a cushioned mounting device for use in mounting an engine to the body of a vehicle such as an automobile.
An engine for an automobile is mounted to the body of an automobile by means of a cushioned mounting device which generally comprises a first frame member fastened to the casing of the engine, a second frame member fastened to the body of the automobile, and a cushion member made of an elastomeric material and provided between and flexibly connecting the first frame member and the second frame member. In this engine mounting structure, as well known in the art, if the spring constant of the cushion member is relatively small, i.e., if the cushion member is relatively soft, although vibration of the engine due to its operation and having a relatively high frequency is well absorbed by the cushion member and transmission of engine vibration from the engine to the vehicle body is effectively interrupted, supporting of the engine becomes unstable and swaying of the engine with a large amplitude is liable to occur when, for example, the automobile is running on a rough ground. Such a large swaying of the engine deteriorates drive feeling of the automobile and would even cause damaging of the engine or the body or the both. On the other hand, if the spring constant of the cushion member is relatively large, i.e., if the cushion member is relatively hard, although supporting of the engine becomes stable and engine swaying is suppressed to a small amplitude, engine vibration is not sufficiently absorbed by the cushion member and drive feeling is also deteriorated, because the natural frequency of the engine support system becomes high and gets closer to the frequency of the exciting force generated in the engine. These two mutually discrepant requirements for the spring constant or softness/hardness of the cushion member has heretofore made designing of the cushioned engine mounting device troublesome and often unsatisfactory.